1. Field of the Invention
The present invention relates to a compact disc (CD) player, and more particularly, to a CD player capable of reproducing signals stored on a CD-OK disk and a video CD.
A CD-OK system reproduces an accompaniment signal, lyrics and background screen for a song which is selected from a compact disc. Typically, the disc can store data (accompaniment and lyrics) for approximately 7,000 songs and approximately 4,000 still images.
FIG. 1 is a block diagram showing the construction of a conventional CD-OK system.
The apparatus shown in FIG. 1 is provided with a system/video controller 108 for generating an address, a sync signal and various control signals necessary for restoring the video data of a CD-OK system; a microcomputer 102 for controlling the system/video controller 108; a program read-only memory (ROM) 100 for storing programs necessary for operating the microcomputer 102; a buffer random access memory (RAM) 104 for temporarily storing data used for the microcomputer; a video RAM 110 for storing image data output from the system/video controller 108; a digital-to-analog converter 112 for converting still image data output from the system/video controller 108 into an RGB signal; a video encoder 116 for converting the RGB signal received from the digital-to-analog converter 112 into a composite image signal according to the address and sync signals supplied from the system/video controller 108 and for outputting the composite image signal; a sound source module 106 for receiving musical instrument digital interface (MIDI) data from a disc (not shown) and thereby generating a CD-OK audio signal; and a switch 118 for selecting either the audio data signal of an external CD, converted via a digital-to-analog converter 120, or the CD-OK audio output from the sound source module 106, and for outputting the selected signal.
A video CD system can reproduce a digital moving picture and digital sound by using a disc storing an image and sound data compressed according to the Moving Picture Experts Group (MPEG) standard.
FIG. 2 is a block diagram showing the construction of a conventional video CD system.
The apparatus shown in FIG. 2 is provided with an MPEG decoder 212 for processing a compressed video signal and a compressed audio signal necessary for video CD operation; a microcomputer 218 for controlling the MPEG decoder 212; a buffer RAM 216 for temporarily storing data which will be used in the microcomputer 218; a micro code ROM 210 for storing programs necessary for operation of the MPEG decoder 212; a video RAM 214 for storing image data of the MPEG decoder 212; a digital-to-analog converter 220 for converting the digital image signal output from the MPEG decoder 212 into an RGB image signal; a video encoder 224 for converting the RGB signal output from the digital-to-analog converter 220 into a composite image signal; and a digital-to-analog converter 226 for converting the digital audio signal output from the MPEG decoder 212 into an analog audio signal and for outputting the converted analog audio signal.
With the above conventional arrangements, the CD-OK and video CD systems require different circuits. Accordingly, when they are integrated into a combined apparatus, the manufacturing cost of the integrated apparatus incorporates a large portion of the costs for each individual device. In addition, the integrated device occupies a large amount of space.